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I headed over to Philadelphia over the weekend to go to a family party.

On Sunday, I went for a run in Fairmount Park. It was pretty cold with a lot of snow on the ground. The wind was unseasonably strong, perhaps 30 mph.

Must be global warming.

I'm sure there's some climate scientologist out there claiming that.

These guys are shameless. If it's warm, that evidence man is altering the climate. If it's cold, that's also evidence of it.

The other day on the radio I heard some climate scientologist citing the recent hurricane as evidence that all Americans should now accept the alleged "consensus" on anthropogenic global warming.

One storm tells us exactly zero about the climate. Weather isn't climate. Or at least that's what the climate scientologists say when the weather in question doesn't support their theory. That cold spell that ruined the big climate conference in Cancun would fit into that category.And as for that alleged consensus, I've noted in the past that it extends only to the small rise in temperature that could be plausibly linked to carbon dioxide added to the climate by human activity.

Those huge swings in climate predicted by charlatans like Al Gore rely on a complex and unproven theory of how clouds respond to that tiny bit of CO-2.

There is little dispute among scientists about how much warming CO2 alone can produce, all other things being equal: about 1.1°-1.2°C for a doubling from preindustrial levels. The way warming from CO2 becomes really dangerous is through amplification by positive feedbacks—principally from water vapor and the clouds this vapor produces.

It goes like this: A little warming (from whatever cause) heats up the sea, which makes the air more humid—and water vapor itself is a greenhouse gas. The resulting model-simulated changes in clouds generally increase warming further, so the warming is doubled, trebled or more.

That assumption lies at the heart of every model used by the IPCC, but not even the most zealous climate scientist would claim that this trebling is an established fact. For a start, water vapor may not be increasing. A recent paper from Colorado State University concluded that "we can neither prove nor disprove a robust trend in the global water vapor data." And then, as one Nobel Prize-winning physicist with a senior role in combating climate change admitted to me the other day: "We don't even know the sign" of water vapor's effect—in other words, whether it speeds up or slows down a warming of the atmosphere.

Climate models are known to poorly simulate clouds, and given clouds' very strong effect on the climate system—some types cooling the Earth either by shading it or by transporting heat up and cold down in thunderstorms, and others warming the Earth by blocking outgoing radiation—it remains highly plausible that there is no net positive feedback from water vapor.

If this is indeed the case, then we would have seen about 0.6°C of warming so far, and our observational data would be pointing at about 1.2°C of warming for the end of the century. And this is, to repeat, roughly where we are.

Meanwhile, alarmists like that guy I heard on the radio are also pointing to the recent spate of droughts as evidence of man-made climate change. Oops. It seems like there's been a drought drought.

At least that's what this paper in Nature says. Here's the conclusion about the flawed models that led to reports of an increase in droughts:

More realistic calculations, based on the underlying physical principles that take into account changes in available energy, humidity and wind speed, suggest that there has been little change in drought over the past 60 years.

As I've pointed out before, there are two debates going on here. One is the debate among scientists, which will continue until they understand the role of CO-2 in cloud formation. The layman has little to say in that regard.

The other is the political debate. Just how much are you willing to have your way of life altered for just how much theoretical benefit to the rest of humanity?

You've got every right to weigh in on that question, boys and girls. And the only consensus that matters is yours, not that of the climate scientologists.